The 50-key Model M was a matrix-style keypad believed to be used with emulating IBM 4700 applications on IBM Personal System/2 or similar class machines. They possessed the same physical layout as the 50-key Model F-based IBM 4704 Model 100 keypads and could come with transparent, functional or alphameric legends. Technically speaking, these are the smallest Model Ms capable of featuring an alphameric layout. These are one of two Model Ms whose internal assembly is based on an older Model F device and thus takes several production values from Model F designs; including individual barrels, metal barrel plate, foam padding, and no plastic rivets holding the assembly together. The assembly's previous incarnation was the 50-key Model F IBM Model 100s these M50s replaced.